A Practical Approach for Modeling Matrix Diffusion Effects in REMChlor

Dr. Ronald Falta | Clemson University

ER-201426

Objective

The objective of this project is to develop practical and efficient mathematical methods for simulating the effects of matrix diffusion in groundwater transport and remediation models. These methods will apply to various types of heterogeneous settings, including fractured porous media and sites with extensive low permeability layers and lenses. The new mathematical methods will then be implemented in the U.S. Environmental Protection Agency groundwater remediation screening model REMChlor to develop a new generation model that considers matrix diffusion in the plume: REMChlor-MD.

ER-201426 Project Photo

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Technology Description

The problem of matrix diffusion of chlorinated volatile organic compounds (CVOCs) in groundwater plumes is mathematically analogous to heat conduction in fractured rocks and heterogeneous reservoirs. Elegant numerical and semi-analytical methods for modeling the heat conduction processes that occur during fluid injection or extraction were developed in the 1980s by geothermal reservoir engineers. With some modifications, these methods are directly applicable to the problem of CVOC matrix diffusion. They offer accurate solutions that do not require explicit discretization of the low permeability zones. Instead, the low permeability zones that occur at scales smaller than a normal numerical gridblock are represented with sub-gridblock scale analytical or numerical approximations. In most cases of interest, these approximations are expected to offer a level of simulation accuracy comparable to the fine-grid numerical simulations, but at a tiny fraction of the computational and user effort.

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Benefits

REMChlor-MD will enable site managers and stakeholders to quickly assess the likely impacts of different source and plume remediation schemes (including natural attenuation) with a comprehensive treatment of matrix diffusion effects. This will reduce overall costs of remediating these sites, and it will help ensure that limited resources for site remediation are used most effectively. (Anticipated Project Completion - 2018)

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Publications

Muskus, N. 2017. Evaluation of a Semi-Analytical/Numerical Method for Modeling Matrix Diffusion Effects in Groundwater Chemical Transport, MS Thesis, Clemson University, December 2017.

Falta, R.W. and W. Wang. 2017. A Semi-analytical Method for Simulating Matrix Diffusion in Numerical Transport Models, Journal of Contaminant Hydrology, 197:39-49.

Wang, W. 2014. Comparison of Analytical, Numerical and Semi-Analytical Methods for Modeling Matrix Diffusion Effects in Aquitards, MS Thesis, Clemson University, December 2014.

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Points of Contact

Principal Investigator

Dr. Ronald Falta

Clemson University

Phone: 864-656-0125

Fax: 864-656-1041

Program Manager

Environmental Restoration

SERDP and ESTCP

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